This invention relates to sockets used for effecting an electric connection between an electronic package and an external device and more particularly to the arrangement of contact elements in such sockets that engage the terminals of the electronic package.
Generally, an IC package is manufactured by sealing an IC chip having an electronic circuit on its main surface with plastic and prior to shipment, the IC packages are subjected to a reliability test called a burn-in test in order to separate acceptable units from unacceptable ones. In conducting this burn-in test, a socket is used for the purpose of effecting an electric connection between the IC package and a substrate used for testing.
As shown in FIGS. 9(a) and 9(b), a plurality of contact pins 104 are arranged on a base 103 of a conventional socket 100 to correspond to the terminal arrangement of an IC package 101 placed in the socket. Each contact pin 104 comprises an anchor portion 104a secured to the bottom of the center of base 103 and a contact part 104b which is elastically biased against a respective terminal of IC package 101. An adaptor 105 is mounted on base 103 for vertical movement relative thereto and is used for seating IC package 101. A plurality of contact holes 106 are formed in adaptor 105 which are somewhat larger than the outer shape of the contact part 104b of contact pin 104. The adaptor 105 accommodates the tip part of a respective contact pin 104 in a contact hole 106.
A latch 107 is provided on base 103 for pressing IC package 101 to open or close in linkage with a vertically movable cover 108. IC package 101 is pushed down along with adaptor 105 as latch 107 applies a force to IC package 101, thereby causing contact pins 104 that have protruded from the contact holes 106 above the seating surface 105a to contact terminals 101a of IC package 101.
This type of conventional socket 100 has certain limitations and problems as will be described below:
Since there are some variation in the size of each contact hole 106 of adaptor 105 and the length of each contact pin, the location of the tip of contact pin 104 and the edge part of the contact hole 106 varies, depending upon the contact pins. Even if the contact pins 104 were to be pressed to the same position at the edge portion of contact holes 106 by bending each contact pin 104 through a lowering of the engagement position of the adaptor, for example, the amount of the protrusion of the contact part 104b of contact pins 104 will vary from the seating surface 105a of adaptor 105.
As a consequence, even if the engagement position of adaptor 105 were to be adjusted so that the contact part 104b of contact pins 104 would not protrude from the seating surface 105a of adaptor 105, as shown in FIG. 10, some contact pins 104 inevitably protrude from seating surface 105a of adaptor 105 due to the variation of the length of the contact pins and the like. When IC package 101 is placed on adaptor 105, therefore, the IC package tends to catch on contact pins 104 that have protruded, thereby interfering with mounting of the IC package.
An object of the present invention is the provision of a socket which overcomes the above described limitations and problems associated with the conventional technology. Another object of the invention is the provision of a socket which is capable of smoothly mounting electronic packages, without the electronic package being caught by the tip part of the contact pins on the seating surface.
Briefly, according to a preferred embodiment of the invention, a socket comprises a base, a cover mounted on the base for alternating motion in the vertical direction relative to the base, first spring members that urge the cover in the upward direction away from the base, a plurality of elongated contact elements each having a first end secured to the base, an intermediate curved part extending from the first end and which can be elastically deformed, a contact part having a second end or contact tip linked to the curved part and which can be elastically pressed against a respective connective terminal of an electronic part, and a protrusion formed at a location which is separated from the second end of the contact element by a selected length. The socket includes a regulator having a plurality of through holes through which the contact part of the contact elements extend in such a way that the regulator is able to engage in an alternating motion in the vertical direction relative to the base, a plurality of control parts for the regulation of the displacement of the contact parts as the control parts engage the protrusion of the contact elements, and a latch member which is provided on the base in such a way as to pivot, making it possible for an electronic package to be inserted by pivoting the latch member from an original closed position to a removed open position in linkage with the downward motion of the cover, and which presses the electronic package that has been mounted in a downward direction by pivoting from the open position to the original closed position in linkage with the return movement of the cover body.
An adaptor is formed with a seating surface for seating the electronic package and second spring members urge the adaptor in an upward direction away from the base. The regulator is also biased in an upward direction away from the base. When the adaptor and the regulator are at their respectively highest locations, a selected distance is provided between the adaptor and the regulator. An electronic package mounted on the seating surface when the latch is in its open position, is pressed against the connective terminals of the electronic package as the latch pivots to its original closed position.
According to a feature of the invention, the tip of the contact parts are disposed below the seating surface when the adaptor is at its highest position. Further, the tip of the contact parts are adapted to be in engagement with the connective terminals of the electronic package on the seating surface when the latch is at its original closed position.
According to a feature of the invention, third spring means in the form of the contact elements themselves bias the regulator in an upward direction relative to the main base.
Additional objects and features of the invention will be set forth in part in the description which follows and in part will be obvious from the description. These objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.